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The RS VAPP Potentiometer Adjustments

The settings below use the Pitch-Tuner software oscilloscope for visual confirmation.


LDR VAPP Board - Volume Amp - Pitch Preview board adjustments.

Begin with all the LDR VAPP Board Pots fully counter-clockwise (off)

Pot 1, Pot 2, Pot 3

Note: A 1/8" stereo jack can be mounted at the VAPP board Power terminal using a stereo plug's middle ring for the Audio to run between the RS Illusion and the VAPP volume control board. The  battery and same on/off switch can then be used for the RS Illusion and the VAPP board. The +V from the RS Illusion is connected to the stereo plug tip and the -V to the back sleeve.

Connect the RS Illusion Audio-Out into the VAPP Audio-In or through a stereo cable using the stereo cable center ring connection. Plug your earpiece into the Pitch Preview stereo jack. Bring the level of brightness of the RS Illusion’s LED 2 to just barely on. Adjust the VAPP Preview Volume Pot 2 for a comfortable listening level in the earpiece.

The LDR sensor volume control has no effect on the Pitch-Preview output.

Attach your LDR volume sensor to the VAPP LDR input terminal. 

*Plug a 1/8" stereo cord plug into the VAPP board Mic-Out stereo jack then the opposite side into your computer Mic-Input on your sound card. Set the VAPP Pot 3 board mounted mic level pot about halfway. This will be readjusted after setting Pot 1 for Line-Out level at the ¼” mono jack. 

Set the Line-Out level to your main amplifier by listening to the speakers set at a normal room volume level. Turn up the VAPP Pot 1 Line Out Volume potentiometer until you hear the ugliness of an overdriven signal then back it down to where it sounds smooth and sweet.

With the Line-Out level set properly, turn down the VAPP Mic-Out Pot 3 for a nice waveform on the computer screen using the Pitch-Tuner software. The display turns red before the peaks have flattened. A little red is ok, watch the oscilloscope wave form and listen for the sound you want. 

Notes: 

You may want to change some of the connections on the pc board using the easy wiring terminals to solid soldered wires on the board to prevent future intermittent loose wire problems. These terminals are mainly beneficial when you're still experimenting and don't want to have anything permanent.

I like to have my volume LDR Sensor (Light Dependent Resistor) on its own stand separate from the main theremin. I could come up with several configuration so do what you think works for you.